Tube bending device

ABSTRACT

A tube bending device for bending tubes of a circular crosssection includes a frame element and a pulley provided with a groove which is firmly attached to the frame element. A steering element for steering the tube during bending has a lever arm which is connected to the steering element and the pulley via a first joint and a second joint. A number of lamellas are arranged in a flexible chain configuration and are linkably but not firmly connected to each other and also provided with grooves. The lammellas are connected to each other via a wire which at its one end is connected to a self-locking abutment or heel member and at its other end to a lamella holder which is pivotably connected to the steering element via a joint which is connected to a stretchable wire.

United States Patent [1 1 Fjellstrom Jan. 15, 1974 TUBE BENDING DEVICE [22] Filed: Sept. 28, 1972 [21] Appl. No.: 293,170

[30] Foreign Application Priority Data Sept 30, 197i Sweden 12360/71 [52] US. Cl. 72/319, 72/369 [51] Int. Cl B21d 11/04 [58] Field of Search 72/318, 319, 369, 72/387 [56] References Cited UNITED STATES PATENTS 2,996,100 8/196! Newhall 72/369 Primary Examiner-Charles W. Lanham Assistant ExaminerRobcrt M. Rogers Attorney-Wenderoth, Lind & Ponack [57] ABSTRACT A tube bending device for bending tubes of a circular cross-section includes a frame element and a pulley provided with a groove which is firmly attached to the frame element. A steering element for steering the tube during bending has a lever arm which is connected to the steering element and the pulley via a first joint and a second joint. A number of lamellas are arranged in a flexible chain configuration and are linkably but not firmly connected to each other and also provided with grooves. The lammellas are connected to each other via a wire which at its one end is connected to a self-locking abutment or heel member and at its other end to a lamella holder which is pivotably connected to the steering element via a joint which is connected to a stretchable wire.

2 Claims, 2 Drawing Figures TUBE BENDING DEVICE The invention relates to a tube bending device for bending of tubes with a circular or next to a circular cross section. Furthermore the invention relates to a tube bending device with a tube bending part or a tube bending mechanism, which is arranged to work automatically during production of complicated tube configurations.

Earlier disadvantages connected to tube bending devices or tools are well known. Those have earlier been discussed in the U.S. Pat. application with the registration number 165824 (the corresponding Swedish patent application has the registration number 5942/70). Conventional devices or tools of said type show up a great many lacks in flexibility and in production results and in quality of a so produced tube bend. Because of large variations in tension when bending a tube with conventional tube bending devices or tools the wall thickness will vary considerably in a cross section of a tube bend. Furthermore the tubes tend to be flattened out near the tube bends, which can lead to crackings along the sides of the tube bend.

The object with this invention is to provide for a tube bending device or tool, in which the abovementioned and earlier disadvantages are eliminated and in which the forming itself of a tube bend is attained through a co-operation between a pulley, which is provided with a groove, and lamellas, which also are provided with a groove and which are not firmly connected to each other but by means of a wire so that a flexible chain of lamellas is obtained, which is swingable around the periphery of the pulley during making of a tube bend. The chain in its turn is steerable via rollers, which are arranged above the individual lamellas, by means of a steering element, which is brought to contact with the rollers during the bending. The wire, which holds the lamellas together is at its one end connected to an abutment or a heel member, which is provided for fixing or locking of the tube at a wished position before bending, and at its other end with a lamella holder, which is pivotably connected to the steering element and via a wire also to a piston, which is arranged in one at a lever arm fixed cylinder. By means of the piston in the cylinder the packet or chain of lamellas and the abutment or heel member is movable in relation to the steering element, whereby a fixing or locking of the tube before bending is provided.

The invention is characterized by the appended claims. The invention will now be described in detail with reference to the appended drawing, where one form according the invention only is shown as an example.

FIG. 1 shows a side elevational view of a tube bending device or tool according the invention.

FIG. 2 shows a cross sectional view of an individual lamella taken along line A-A in FIG. 1.

In FIG. 1 a frame element is denoted with 8, a pulley, which is provided with a groove, with 7 and a steering element with 4. The pulley 7 and the steering element 4 are pivotably connected to each other by means of a lever 6 via joints l5 and 14. A number of lamellas 2, which are provided with a groove 10, are arranged in a chain configuration and are not firmly connected to each other but via a flexible wire 3, which is arranged to run in at the lamellas provided grooves or holes. The individual lamellas 2 are at their upper part provided with bearing rollers 5, which are pivotably attached to the lamellas, whereby the steering element during bending of a tube is brought into contact with the rollers for transferring of the bending force to the bend. Because of that the bending force during the bending is transferred from the steering element 4 to the tube bend via those rollers 5 and the lamellas 2, this force transfer will be tolerably frictionless. The chain or packet of lamellas is swingable around the periphery of the pulley 7 by means of a lever arm 6. The wire 3 is at its one end 17 connected to an abutment or a heel member 1, which is provided for fixing or locking of the tube 12 before bending, and at its other end to a lamella holder 13, which is pivotably connected to the steering element 4 via a joint 16. The frame element is provided with inclined grooves 18, in which the heel member is arranged to run. When stretching a wire 11 the heel member 1 will be pulled forward towards the steering element 4 and at the same time like a wedge be pressed in between the tube 12 and a wedgeshaped element 8', which is attached on the frame element 8. The abutting element or the heel member 1 and the the lamellas are kept together by means of the wire 3 and form a packet or chain, which is movable in relation to the steering element 4. When the: wire 3 is detached after a finished bending and the steering element 4 is moved back to its origin position the heel member will be moved backwards along the inclined grooves 18 and brought out of contact with the tube 12. The stretching of the wire 3 is effected by means of one at the lever arm 6 firmly fixed cylinder 9, the piston axle of which via the wire 11 is connected to the lamella holder 13, which is pivotably attached to the steering element at the joint 16. When the piston axle is pulled in towards the cylinder the wire 11 accordingly will be stretched, whereafter the wished bend is accomplished when the lever arm 6 is pivoted around the joint 15, whereafter the packet or chair of lamellas and the steering element are brought to follow along the periphery of the pulley 7.

The groove 10 of the lamellas and the grove of the pulley form a non-circular channel, which preferably has a form of an ellipse or a hyperbola. Hereby it will be prevented that the tube will flatten out at the tube bend. Furthermore an even wall thickness is obtained at the tube bend, opposite to that what will happen when a tube bend is made in conventional tube bending devices or tools. The form of the channel formed between the pulley and the lamellas are earlier described in the U.S. patent application with the registration number 165824(the corresponding Swedish petent application has the registration number 5942/).

The tube bending device according the invention can be modified in several ways without departing the scope of the invention, that will be evident for those skilled in the art and that appears from the appended claims.

I claim:

1. A tube bending device for bending of tubes with a circular or next to circular cross section, which device comprises a frame element 8, a pulley 7, which is provided with a groove and which is firmly attached to the frame element, a steering element 4 for steering of the tube during the bending, characterized by, that a lever arm 6 is provided,which is connected to the steering element (4) and the pulley 7 via a first joint 14 and a second joint 15, that a number of lamellas 2 are arranged in a flexible chain configuration, which lamellas are linkably but not firmly connected to each other and also provided with grooves 10, whereby the lamellas are connected to each other via a wire 3, which is arranged to run in at the lamellas arranged grooves or holes, which wire 3 at its one end 17 is connected to a self-locking abutment or heel member 1 and at its other end to a lamella holder 13, which is pivotably connected to the steering element via ajoint 16 and which is connected to a stretchable wire 1 1,whereby the abutment or heel member 1 is arranged in the frame element in such a way, that the heel member before the bending can be pulled towards the pulley 7 and the steering element 4 and at the same time be brought to contact with the tube 12 with the view to lock or fix the tube at a wished position by means of a cylinder 9, which is firmly attached to the lever arm 6 and whereby the piston of the cylinder is connected to the lamella holder 13 via the wire 11, that bearing rollers 5 are pivotably arranged on the upper part of the lamellas 2, with which rollers the steering is arranged to be brought into contact during the bending,whereby a tolerably frictionless transfer of the bending forces from the steering element to the tube bend is obtained.

2. A tube bending device according claim 1, charactarized by, that the abutment or heel member 1 is arranged to run in inclined grooves, which are arranged in one at the frame element 8 attached wedgeshaped part 8, in such a way,that said heel member 1 is pressed like a wedge between the frame element 8 and the tube 12 when it is pulled towards the steering element 4, and which heel member 1 after finished bending and when the steering element 4 is moved back to its origin position again is brought out of contact with the tube. 

1. A tube bending device for bending of tubes with a circular or next to circular cross section, which device comprises a frame element 8, a pulley 7, which is provided with a groove and which is firmly attached to the frame element, a steering element 4 for steering of the tube during the bending, charactarized by, that a lever arm 6 is provided, which is connected to the steering element 4 and the pulley 7 via a first joint 14 and a second joint 15, that a number of lamellas 2 are arranged in a flexible chain configuration, which lamellas are linkably but not firmly connected to each other and also provided with grooves 10, whereby the lamellas are connected to each other via a wire 3, which is arranged to run in at the lamellas arranged grooves or holes, which wire 3 at its one end 17 is connected to a selflocking abutment or heel member 1 and at its other end to a lamella holder 13, which is pivotably connected to the steering element via a joint 16 and which is connected to a stretchable wire 11, whereby the abutment or heel member 1 is arranged in the frame element in such a way, that the heel member before the bending can be pulled towards the pulley 7 and the steering element 4 and at the same time be brought to contact with the tube 12 with the view to lock or fix the tube at a wished position by means of a cylinder 9, which is firmly attached to the lever arm 6 and whereby the piston of the cylinder is connected to the lamella holder 13 via the wire 11, that bearing rollers 5 are pivotably arranged on the upper part of the lamellas 2, with which rollers the steering is arranged to be brought into contact during the bending, whereby a tolerably frictionless transfer of the bending forces from the steering element to the tube bend is obtained.
 2. A tube bending device according claim 1, charactarized by, that the abutment or heel member 1 is arranged to run in inclined grooves, which are arranged in one at the frame element 8 attached wedgeshaped part 8'', in such a way, that said heel member 1 is pressed like a wedge between the frame element 8 and the tube 12 when it is pulled towards the steering element 4, and which heel member 1 after finished bending and when the steering element 4 is moved back to its origin position again is brought out of contact with the tube. 